/Engine/Source/Runtime/SlateCore/Public/Application/SlateApplicationBase.h
Gets whether or not a particular widget has mouse capture by a user.
True if the widget has mouse capture, otherwise false.
bool DoesWidgetHaveMouseCaptureByUser ( const [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< const [SWidget](API\Runtime\SlateCore\Widgets\SWidget) > Widget, int32 UserIndex, [TOptional](API\Runtime\Core\IO\TOptional)< int32 > PointerIndex ) const